Electric condenser



Dec. 23, 1930. E. SHAW ELECTRIC CONDENSER Filed Dec. 29, 1923 INVENTOR Louz'sEfi/zazu ATTORNEY Patented Dec. 23, 1930 UNITED STATES PATENT OFFICE LOU' IS E. SHAW, OF EAST ORANGE, NEW JERSEY, ASSIGNOR, BY MESNE ASSIGNMENTS, TO DEJ'UB-AMSCO CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK ELECTRIC CONDENSER Application filed December 29, 1923. Serial No. 683,269.

This invention relates to a variable electric condenser, and relates more particularly to an electric condenser in which the movable or rotor unit is conductively connected to the supporting frame therefor and the stationary or stator unit is insulatably mounted on said frame; and has special reference to the provision of a variable condenser of the vernier type.

The general ob'ect of the invention is to provide a simpli ed and improved form of variable condenser of the type above outlined and incidentally, to provide a mechanical construction which will feature all the necessary accuracy in the positioning of the several parts and at the same time will minimize necessity of employing skilled labor and thus provide a construction which can be readily fabricated cheaply in large numbers as a factory production.

Another object of the invention is to provide a construction which will permit of a. sensitive control of both the main plate adjustment and the vernier adjustment and by means of which both adjustments may be attained independently of each other. Incidental to this feature is the providing of a form of friction brake which is particularly efficient for the purpose of controlling shafts of such instruments and which can be readily replaced when worn. Still another object of the invention is to provide a form of air gap condenser which features the minimizing of mass of necessary dielectric used and consequential minimizing of leakage through imperfect forms of dielectrics.

Still another object of the invention is to the invention also consists in certain new and novel features of construction and combination of parts hereinafter set forth and claimed.

In the accompanying drawings Figure 1 is a vertical sectional view taken axially of the control shafts through a re ferred embodiment of the invention and ta en on the line 11 of Figure 2; and

Figure 2 is a transverse sectional view taken on the line 2-2 of Figure 1 looking in the direction indicated by the arrows.

In the following description and in the claims, parts will be identified by specific names for convenience of expression but they are intended to be as generic in their application to similar parts as the art will permit.

The condenser includes a skeletonized, metallic instrument and comprises a front frame 10. a rear frame 11. each in the form of a substantially flat rectangular plate cored out as shown at 12 in Figure 2. The two plates are connected together at each corner bv 'means of holding posts13 so that the front and rear frames are connected physically and electrically by the small posts. It is'a feature of this disclosure that the holding posts are positioned exteriorly of the outlines of both the stator plate and rotor plate assemblies and are removed as far as possibleout of the electric condenser field.

The front frame 10 is provided with a plurality of bosses, one of which is shown at 13a by means ofwhich the condenser as a whole may be mounted on a suitable support, such as the instrument board 14 shown in dotted lines, Figure 1.

A stator plate assembly in the form of a manufactured unit distinct from the frame is demountably positioned between the frames 10 and 11. This assembly comprises a plurality of stator plates 15 threaded loosely on three spaced apart clamping rods 16, 17 and 18 and spaced apart on the several rods by spacing washers 19. Opposite ends of each of the rods is threaded as shown at 20 and 21 in the case of the rod 17. These threaded portions are engaged by clamping nuts 22, 23 which act to clamp the plates therebetween. From this construction it will be understood that the washers 19 act to space the plates properly and that the plates are supported on and held together by spacer members. By manipulation. the nuts 22 and 23 at opposite ends of each of the rods, the stator plate assembly as a whole-may be adjusted relative to the ends of the rod and in this way the stator plates may be adjusted relative to the rotor plates hereinafter described. The nut 23 may be utilized to clamp one of the usual leads to the stator plate assembly. The ends of the rods are'reduced to form abutting shoulders 24 and to form reduced plug ends 25. The frames 10 and 11 are provided with apertures arranged in pairs opposite the position where the rods 16, 17 and 18 are to be located and in each of these apertures is positioned a headed button or stud or pedestal insulator 26 of insulating material. The inner face 27 of these stud insulators is designed to be engaged by the adjacent shoulder 24 and the shoulder engaged buttons coact to prevent axial movement of each rod in both directions. The face 27 of each insulator is provided centrally thereof with a socket recess 28 into which is fitted the adacent end of the-engaging rod. It is a feature of this disclosure that the dielectrics or insulators are of relatively small mass and while suflicient to insulate the op positely charged parts, the mass exposed to the oppositely charged parts has been reduced to a minimum so as to reduce dielectric losses to a minimum. It will also be seen that by means of this construction the rotor unit is conductively connected to the supporting condenser frame, the rotor, rotor shaft and condenser frame being therefore of the same potential. It will also be seen that a construction is provided which may be readily assembled by interlocking or inter-engaging the insulators with the end plates of the supporting frame and by similarly interlockingthe spacer members of the stator unit with said insulators, the posts connecting the end plates functioning for holding the parts in assembled relation.

It is understood from this construction that the stator plate assembly can be fabricated as a unit and marketed as a replacement part. To complete the structure as thus far described, the stud dielectrics are inserted in place in the front and rear frames, and the stator plate assembly mounted in position alternating with the rotor plates, after which the holding posts can be mounted and secured to the frames which thus holds the stator plate assembly in position. The parts are thus arranged so that the instrument may be easily demounted simply by demounting the several holding posts.

The rotor plate assembly 29 resembles conventional structule and is mounted on a hollow main shaft 30, herein also referred to as a rotor plate shaft, which has opposite ends rotatably mounted in bearing bosses 31 and 32 extending inwardy respectively from the frames 10 and 11. The main shaft is extended forwardly from the instrument so as to extend through the mounting board 14 and is manipulated by a dial knob 33 of conventional form. The main shaft is provided in rear ofthe boss 31 with an enlarged shouldered portion 34 which engages a waslier 35 disposed between the same and the rear face of the boss 31 to limit forward axial movement of the shaft. This shoulder portion also constitutes a fixed stop for limiting the movement in one direction of the rotor plate assembly. This assembly comprises a plurality of rotor plates 35 threaded loosely for axial adjustment on the main shaft. and maintained in fixed spaced apart relation by spacing washers 36. At the rear end of the rotor plate assembly the main shaft is threaded as shown at 37 and this portion is engaged by a jam or binding nut 38 acting to force the rotor plates and their washers bodily into engagement with the shoulder 34 and in this way the rotor plate assembly is secured rigidly to the shaft to turn therewith. The nut 38 also acts to prevent abnormal axial movement of the main shaftrearwardly through the bearing provided by the boss 32.

The main shaft is provided with a friction brake 39 of the disk type disposed to restrain the freedom of rotary movement of the shaft. In order to accommodate the brake, the front face of the frame 10 is recessed about the main shaft in order to provide a countersunk pocket 40 havinga flat bottom 41 disposed in a plane normal to the axis of rotation of the shaft. This surface is engaged by one side of a. flat washer 42 of some compressible material usually used for this purpose, such as felt. The opposite side of the washer is engaged by a follower plate 43, mounted loose on the shaft and maintained in bearing engagement with the felt disk by means of a spring spider 44. This spider is carried by a sleeve 45 slidably mounted on the main shaft and held in adjusted position thereon by means of a clamping screw 46. One free end of the spider engages in a radially disposed slot 47 formed on the outer face of the follower plate. The spring spider acts automatically to take up wear on the friction brake and acts to transmit rotary movement from the main shaft to the follower plate. By adjusting the position of the sleeve 45 any de sired tension may be given the spring. The broad bearing surface between the follower plate and the felt disk provides a relatively extensive friction surface which insures the maintaining of the shaft in whatever position it may be set and at the same time the degree of resistance to rotary movement may be readily adjusted so as not to interpose an abnormal resistance to the manual manipulation of the shaft.

The hollow main shaft provides a support for a long solid vernier shaft 48 which extends through the bore of the main shaft with a loose fit therein and it is understood that these shafts are otherwise independent of each other. The vernier shaft'projects forwardly of the main shaft and is itself provided with a manipulating knob 49. The vernier shaft projects rearwardly through the rear frame 11 and terminates in a rounded head 50 which is engaged by the free end of a spring contact 51 secured to the frame 11 by screws 52. The screws constitute a binding post for securing a conductor 53 designed to supply electric energy to the condenser parts including the rotor assembly in all rotary positions of the rotor plates. A vernier plate 54 is provided with an inner cylindrical flange 55 constituting a hub rotatably mounted upon the outer cylindrical face of the bearing 32. It is a feature of this disclosure that the vernier plate is mounted independently of the main shaft so that wabbling or other irregular movement of the main shaft will-not affect the relation of the vernier plate to its adjacent. stator plate 56. In order to insure the maintenance of the vernier plate in a plane parallel to the adjacent stator plate and in a plane perpendicular to the axis of rotation, the hub 55 is inturned slightly to provide more than an edge bearing on the cylindrical boss 32and the adj acent portion is designed to fit flat against a portion of the rear frame.

In the present disclosure the Vernier plate is in the form of a cup shaped stamping 57 from the outer flange 58 of which projects a flat plate59 constituting, in effect, the end member of the rotor plates. The flange 58 is provided with a small aperture 60 in which is positioned the pointed end 61 of one depending leg of a U-shaped rocking arm 62 which overhangs the top of the frame 11. The other leg 63 of which is secured rigidly to the projecting end of the vernier shaft by the upsetting of the end of this shaft in forming the rounded contact head 50.

The vernier plate is provided with a friction brake 64 resembling the brake 39. Here again the front face of the rear frame is re cessed to provide a pocket 65 in which is positioned a felt washer 66 engaging the bottom of the recess on one side and the opposite side of which is engaged by the bottom 67 of the cup shaped portion of the vernier plate. A compensating spider spring 68 bears on the bottom of the cup shaped portion to take up wear and this spring in turn is demountably held in position by a locking ring 69.

In operation it is understood that the condenser herein disclosed functions as is usual with similarly designed condensers now in general use. The knob 33 is rotated to swing the rotor plate assembly relative to the stator plate assembly until the approximate degree of overlapping of the plates is attained, after which the knob 49 is manipulated to obtain the desired variation provid-,

ed by the Vernier plate construction.

The two braking constructions coact so that either shaft may be manipulated without dragging the other .and each of the shafts will remain set in whatever position they may be adjusted. When once set in position the several plates are fixed and in this way the air gap between adjacent plates may be reduced to a minimum and thus provide an extremely sensitive instrument within a small 'over all space.

TVhile I have shown and described, and have pointed out in the annexed claims, certain novel features of my invention, it will be understood that various omissions, substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

Having thus described my invention; I claim:

1. In an electric condenser, the combination of a frame provided on one side with a recess, a rotor plate shaft journalled in the frame and projecting therefrom centrally through said recess, a follower plate carried loose on the shaft and positioned in said recess, a, felt disk between the follower plate and the bottom of said recess and a spring spider secured to the shaft and bearing at its free end against the follower plate to cause the same to turn with the shaft and at the same time-to bear against the felt disk and in turn force the same against the frame at the bottom of the recess.

2. In an electric condenser, the combination of a support, a rotor plate shaft journalled in the support, a follower plate loose on the shaft, a compressible disk disposed between the support and the plate and coacting therewith to form a friction brake of the disk type, the outer face of the plate proprovided with a slot and acompensating spring having one end secured to the shaft and the other end engaging in said slot and acting on the plate to cause the same to turn with the shaft, to cause the plate to move axiallyof the shaft, bear on the compressible disk and to take up wear on the several parts of the brake and thus maintain-the brake in operative condition.

3. In an electric condenser, the combination of a support, a rotor plate element mounted for rotary movement relative to said support, a felt disk between the element and the support and a compensating spring acting on said element for moving the same in the direction of its axis of rotation and for causing the same'to bear on the felt disk.

4. In an electric condenser, the combination of a frame provided with a boss, a holsaid shaft, a vernierplate provided with a hub mounted for rotary movement on said boss, a backing for the Vernier plate, said hub having a bearing on the boss'coacting with the backing to minimize any tendency of the vernier plate to move out of'its plane of rotation.

5. In an electric condenser, a Vernier plate construction comprising a cup shaped stamping provided with a flat plate projecting outwardly from one edge, the outlining flange of the cup provided with means for rotating the plate construction. I 6. In an electric condenser, a Vernier plate construction comprising a cup shaped stamping provided with a flat plate projecting outwardly from one edge, the outlining flange of the cup provided with means for rotating the plate construction and said cup provided at its center with an inner flangeconstituting a hub for mounting the construction for rotary movement.

7 In an electric condenser, the combination of a support, a Vernier plate mounted for rotary movement on the support, a flat felt washer disposed between the support and the Vernier plate, a spring acting on the Vernier plate and tending to force the same axially into frictional engagement with the washer and means for rotating the Vernier plate to turn the same against the resistance pro-.,'

vided by said washer.

8. In an electric condenser, means providing a friction brake of the rotating disk face type, said means including a Vernier plate as one of its rotating elements.

9. In an electric condenser, the combination of a frame, a hollow main shaft journalled at one end in said frame, a Vernier shaft journalled in the bore of the mainshaft and projecting therefrom beyond the frame, a

Vernier plate journalled on the frame, a U- arm secured by one of its legs to the proj ectcd end of the Vernier shaft and connected by its other arm to the Vernier to rotate the same.

10. In an electric condenser, the combination of a frame, a hollow main shaft journalled at one end in said frame, a verni'er shaft journalled in the bore of the main shaft and projecting therefrom beyond the frame, a Vernier plate journalled on the frame, a U- arm secured by one of its legs to the projected end of the Vernier shaft and connected by its other leg to the Vernier to rotate the same and a spring bearing on the end of the Vernier shaft to hold the same in place.

11. In an electric condenser, the combination of a frame, a hollow main shaft journalled at one end in said frame, a Vernier shaft journalled in the bore of the main shaft and projecting therefrom beyond the frame, a Vernier plate journalled on the frame, a U- arm secured by one of its legs to the projected end of the Vernier shaft and connected by its other leg to the Vernier to rotate the same and a spring bearing on the end of the Vernier shaft to hold the same in place, said spring constituting an electric contact for conveying electric energy to the Vernier plate.

12. A variable condenser construction comprising in combination a pair of end plate portions, a plurality of stator plates positioned between said end plate portions, spacer members at opposite ends of said plates for positively spacing each of said plates one rom another and a lurality of pedestal insulators interposed etween said end plates and said spacer members for supporting said stator plates apart from said end plate portions. j

13. A variable condenser construction comprising in combination a pair of end plates, a plurality of posts interconnecting said end plates forming a frame, a plurality of stator platescarried within said frame, a pair of spacer members at opposite ends of said plates positively spacing said plates apart and a plurality of insulated posts interposed between said spacer members and said end plates.

14. A variable condenser comprising a frame including a pair of metallic end plates and posts interconnecting the end plates, a rotor plate set unit including a rotor shaft and plates secured thereto journalled in and con- ,ductively connected to the metallic end plates of said frame, a stator plate set unit includ ing spacer members and stator plates secured thereto and pedestal insulators interposed between the said end plates and the spacer members supporting said stator unit from the opposite end lates of said frame.

15. A varia le air condenser comprising a rotor plate set, end supporting plates therefor, a stator plate set and means supporting the stator plate set on the end supporting plates, the said means consisting of a plurality of insulators carried by the end plates and carrying the stator plate set, the said end plate, stator plate set and insulators being provided with integral inter-engaging means effective for locking the stator plate set in supported position.

Signed at New York city, in the county of New York and State of New York, this 15th day of October, A. D. 1923.

LOUIS E. SHAW. 

